skip to main content

DOE PAGESDOE PAGES

Title: Magnetic brightening and control of dark excitons in monolayer WSe2

Monolayer transition metal dichalcogenide crystals, as direct-gap materials with strong light-matter interactions, have attracted much recent attention. Because of their spin-polarized valence bands and a predicted spin splitting at the conduction band edges, the lowest-lying excitons in WX 2 (X = S, Se) are expected to be spin-forbidden and optically dark. To date, however, there has been no direct experimental probe of these dark excitons. Here, we show how an in-plane magnetic field can brighten the dark excitons in monolayer WSe 2 and permit their properties to be observed experimentally. Precise energy levels for both the neutral and charged dark excitons are obtained and compared with ab initio calculations using the GW-BSE approach. As a result of their spin configuration, the brightened dark excitons exhibit much-increased emission and valley lifetimes. These studies directly probe the excitonic spin manifold and reveal the fine spin-splitting at the conduction band edges.
Authors:
; ; ; ; ; ; ; ; ; ; ;
Publication Date:
Grant/Contract Number:
AC02-05CH11231
Type:
Accepted Manuscript
Journal Name:
Nature Nanotechnology
Additional Journal Information:
Journal Volume: 12; Journal Issue: 9; Related Information: © 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.; Journal ID: ISSN 1748-3387
Publisher:
Nature Publishing Group
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
OSTI Identifier:
1458504

Zhang, Xiao-Xiao, Cao, Ting, Lu, Zhengguang, Lin, Yu-Chuan, Zhang, Fan, Wang, Ying, Li, Zhiqiang, Hone, James C., Robinson, Joshua A., Smirnov, Dmitry, Louie, Steven G., and Heinz, Tony F.. Magnetic brightening and control of dark excitons in monolayer WSe2. United States: N. p., Web. doi:10.1038/nnano.2017.105.
Zhang, Xiao-Xiao, Cao, Ting, Lu, Zhengguang, Lin, Yu-Chuan, Zhang, Fan, Wang, Ying, Li, Zhiqiang, Hone, James C., Robinson, Joshua A., Smirnov, Dmitry, Louie, Steven G., & Heinz, Tony F.. Magnetic brightening and control of dark excitons in monolayer WSe2. United States. doi:10.1038/nnano.2017.105.
Zhang, Xiao-Xiao, Cao, Ting, Lu, Zhengguang, Lin, Yu-Chuan, Zhang, Fan, Wang, Ying, Li, Zhiqiang, Hone, James C., Robinson, Joshua A., Smirnov, Dmitry, Louie, Steven G., and Heinz, Tony F.. 2017. "Magnetic brightening and control of dark excitons in monolayer WSe2". United States. doi:10.1038/nnano.2017.105. https://www.osti.gov/servlets/purl/1458504.
@article{osti_1458504,
title = {Magnetic brightening and control of dark excitons in monolayer WSe2},
author = {Zhang, Xiao-Xiao and Cao, Ting and Lu, Zhengguang and Lin, Yu-Chuan and Zhang, Fan and Wang, Ying and Li, Zhiqiang and Hone, James C. and Robinson, Joshua A. and Smirnov, Dmitry and Louie, Steven G. and Heinz, Tony F.},
abstractNote = {Monolayer transition metal dichalcogenide crystals, as direct-gap materials with strong light-matter interactions, have attracted much recent attention. Because of their spin-polarized valence bands and a predicted spin splitting at the conduction band edges, the lowest-lying excitons in WX 2 (X = S, Se) are expected to be spin-forbidden and optically dark. To date, however, there has been no direct experimental probe of these dark excitons. Here, we show how an in-plane magnetic field can brighten the dark excitons in monolayer WSe 2 and permit their properties to be observed experimentally. Precise energy levels for both the neutral and charged dark excitons are obtained and compared with ab initio calculations using the GW-BSE approach. As a result of their spin configuration, the brightened dark excitons exhibit much-increased emission and valley lifetimes. These studies directly probe the excitonic spin manifold and reveal the fine spin-splitting at the conduction band edges.},
doi = {10.1038/nnano.2017.105},
journal = {Nature Nanotechnology},
number = 9,
volume = 12,
place = {United States},
year = {2017},
month = {6}
}

Works referenced in this record:

Emerging Photoluminescence in Monolayer MoS2
journal, April 2010
  • Splendiani, Andrea; Sun, Liang; Zhang, Yuanbo
  • Nano Letters, Vol. 10, Issue 4, p. 1271-1275
  • DOI: 10.1021/nl903868w

Electron correlation in semiconductors and insulators: Band gaps and quasiparticle energies
journal, October 1986

Atomically Thin MoS2 A New Direct-Gap Semiconductor
journal, September 2010